BigStrat – Stratification of Large Thermal Storage Tanks

A combination of measurements from seven field systems and simulations of systems with large thermal storage tanks was used in order to derive rules for the extrapolation of design rules that lead to good thermal stratification from small (800 l) sized tanks to large (up to 200 m³) tank sizes. In addition, a deflection relation was defined that allows for the prediction of the preservation of existing stratification depending on the distance to the next obstacle in the storage tank, when fluid is entering vertically or via an elbow pipe in the direction of the storage tank cover.

Sol-Ind Swiss – Solar process heat in the Swiss market

In Switzerland the industry share of the total energy demand is 19 %. Half of this energy is used for the conversion to process heat and is mainly provided by fossil fuels [SFOE, Swiss national statistics 2014]. In a feasibility study the use of solar process heat by systems with solar thermal collectors therefore shows great potential and will in more detail examine the integration in the energy supply systems. In this study we restrict to a temperature range below 130 °C. For this purpose, it is necessary to identify the Swiss companies, which have the majority of the thermal energy consumption at temperatures below 130 °C. Furthermore, within the framework of the project, standardized system solutions for the planning and integration of a solar thermal system will be developed on the basis of three case studies. The focus lays on the yield calculation of the plant taking the location into account, the costs for the collector field and integration as well as the CO₂ savings by replacing fossil fuels through solar energy.

Siphon – Recommendation for heat traps of thermal energy storages

The installation of heat traps is state of the art for pipes that are connected to thermal energy storage units but that are not permanently operated, i.e. the fluid in the pipe is not flowing continuously. In this project, the SPF investigates on issues that created uncertainty within the planning and installation community, such as the question of the significance and effect of insulation in the region of the actual heat trap.

Abstorex – Seasonal thermal storage system for solar energy

A 1 kW closed sorption thermal energy storage system (TES) prototype is set-up and tested at HSR-SPF. This can be charged in summer with heat from solar thermal collectors or with electricity from photovoltaic modules. The system can achieve a significantly higher volumetric energy density compared to sensible hot water storage. The closed sorption system is designed to work with different sorbent-sorbate pairs (NaOH-H₂O, LiBr-H₂O and LiCl-H₂O). Scaling to larger units with correspondingly higher power will be done in the frame of SCCER HaE (Heat and Electricity).

Photovoltaic-Thermal (PVT) solar collectors simultaneously generate useful solar heat and electricity and thereby reach high area specific energetic yields. In the past few years, an increasing interest in PVT collectors could be observed. New products were developed and brought to the market and, particularly in Switzerland, a number of PVT plants were built. On behalf of EnergieSchweiz (a programme by the Swiss Federal Office of Energy) SPF is leading a study on the current PVT market, the state of the art of PVT technology, and on the experiences made by the various actors that have been involved in the realization of PVT plants.

In this project a measurement device for the determination of the specific heat capacity of heat transfer fluids was developed. This device allows us to measure the specific heat capacity with an accuracy of ± 0.3 – 0.5 %, which is a great advantage compared to standard methods as e.g. DSC (Differential Scanning Calorimetry) that commonly provides an accuracy of only ± 3 – 5 %.

Accuracy values for the specific heat capacity create more confidence into your products. Especially for monitoring of energy balances of heating and cooling applications this is indispensable.

ErrEnEff – Influence of individual room controllers on the heating demand of a single family house with low temperature heating distribution

In Switzerland standards allow floor heating systems without individual room controllers, as long as the calculated design flow temperature is below 30 °C. The argumentation is that a self-regulating effect comes into operation, because of the low temperature differences between heating surface and air temperatures. In the master thesis of Igor Mojic (part 1), it was investigated, whether the use of thermostatic valves leads to energy savings in the case of heat distribution systems with low flow temperatures. Based on the master thesis a second study was done with inputs from the AWEL Zürich (part 2).

The goal of the present project is to analyse the technical and economic feasibility of a solar-ice system based on a super-cooling slurry heat pump. The system should achieve higher electricity savings and overall system performance with a comparable return on investment with respect to state-of-the-art ground source heat pump and solar-ice solutions. The anticipated efficiency increase is based on the super-cooler heat exchanger which is always free of ice. The anticipated cost reduction is based on the use of very simple storage vessels that do not need build-in heat exchangers.

ImmoGap – Influence of user behaviour and building system technologies on the performance gap of large buildings

This project analyses multifamily homes that show a large gap between the predicted and the achieved energy performance, and determines the cause for these performance gaps. The combined effects of user behavior and the building technology and control are analyzed. From this analysis, options for action for planers and pubic authorities are deduced.

SWSG – Feasibility of solar assisted district heating networks in the canton of St.Gallen

Solar assisted district heating is widely used in countries as Austria, Germany and Sweden and is booming in Denmark. Heat production costs below 0.05 CHF/kWh where recently reached. With this feasibility study district heating networks of the canton of St. Gallen are analyzed in terms of the feasibility and the cost-benefit ratio of an integration of large solar thermal collector field. A further goal is to make contact between collector manufacturers and network operators as well as to initiate the realization of several large collector fields.

SWSG is supported by the canton of St.Gallen and the Swiss Federal Office of Energy (SFOE).

ReSoTech – Reduction of Market Prices of Solar Thermal Systems due to New Technological Approaches – Phase 1: Analysis of Potentials and Possible

The potentials of cost reduction of solar thermal systems will be derived with cost data that will be gathered from field installations. The use of new technologies and materials for the exploitation of relevant potentials for cost reduction will be assessed. System concepts with reduced costs will be designed, which will contain newly developed components and which will have a high degree of faultlessness during installation and operation.

This project is financed by the Swiss Federal Office of Energy (SFOE).

CombiVolt – Influence of smart heat pumps on PV self-consumption and on the electrical grid

Several companies develop or already offer "smart heat pumps" on the market which combine heat pumps (HP) with photovoltaics (PV). These heat pumps are advertised to optimize self-consumption of the PV electricity as well as to deliver grid services to the utilities. In the CombiVolt project, the influence of intelligent control for heat pumps on both (self-consumption and grid-stability) is analyzed based on whole system testing in the lab in combination with simulations. The options to increase self-consumption by means of electrical or thermal storage are compared. Thereby the current tariff-schemes of today are considered as well as future scenarios for PV penetration and electricity tariffs.

SCCER EIP – Industrial process heat with renewable energy sources

In order to push the energy transition seven Swiss Competence Centers for Energy Research (SCCER) have been launched by the Commission for Technology and Innovation (CTI). One of them, the SCCER EIP (Efficiency of Industrial Processes), focuses on the question of how to support industry to enhance the energy efficiency and reduction of CO₂ emission in order to reach the goals of the Swiss national «Energy Strategy 2050». The SPF is part of this consortium and supports industry partners in better management of energy consumption by energy flow analysis and by the investigation on the integration of renewable energy sources for process heat.

EvaSP – Evaluation of solar process heat systems

The interest in solar process heat for industrial applications is increasing worldwide. For future perspectives and realization of further solar collector fields an assessment of the current state is necessary.

Within the framework of the project EvaSP (Evaluation of solar process heat systems) funded by the Swiss Federal Office for Energy SFOE, several solar collector fields used for processes heat in different industrial branches are energetically and economically evaluated. This project will give an overview of the performance of these collector fields as well as suggestions for suppliers and planners. Furthermore, the results of this evaluation will aid entrepreneurs and investors in the decision-making process and support the implementation of solar thermal energy in industry.

SolProof – Compactness and fault resistance of solar heating systems

The competition between photovoltaics and solar thermal systems for available roof area and investment capital of house owners is putting pressure on solar thermal heating systems to reduce cost and to simplify the product. This project aims to assist manufactures in this task. The goal is to reduce the complexity of solar thermal systems, and reduce likelihood of failures during planning and installations. Criteria for defining compactness and fault resistance will be defined and subsequent applied to different heating systems in the test bench. For this purpose, the well-established CCT method will be simplified and combined with the criteria for evaluation of compactness and fault resistance.

This project is financed by the Swiss Federal Office of Energy (SFOE).

IceEx – Characterization of heat exchanger concepts for ice storages

Ice storages in combination with solar thermal collectors and a heat pump to provide domestic hot water and space heating demands (solar-ice systems) are a promising technology. The project IceEx aims at characterizing heat exchanger concepts for ice storages in solar heating applications. Several heat exchangers, available on the market or recently developed for solar-ice systems, are analyzed by means of experiments and simulations to find an optimum design. Transient yearly simulations are used to assess the system efficiency and energy demand.

This project is financed by the Swiss Federal Office of Energy (SFOE).

ColourAge – Lifetime assessment of aluminium based absorber coatings

There is a lack of knowledge on the lifetime assessment of modern solar selective absorbers. In the project ColourAge, the performance and durability of different aluminium based coatings are studied. The combined effect of high humidity, condensation and temperature on the degradation of optical and chemical properties is assessed. Advanced techniques for materials characterization were used to identify the main degradation mechanisms: surface/interface (XPS, TEM) and chemical (EDX) analysis, as well as optical measurements (UV-Vis-NIR and FTIR spectroscopy).

In this P&D project three identical minergie-A multifamily houses where equipped with three different solar assisted heating systems: PV, PVT and solar thermal with flat plate collectors. The heating systems are equipped with ground source heat pumps and controlled by a newly developed predictive and adaptive control. In the buildings with solar thermal plant the ground source is regenerated. The third building with PV and ground source without regeneration serves as a reference system. Temperature sensors at a depth of 50 m, 110 m and 170 m allow the evaluation of temperatures in the ground over time for each of the three borehole fields. The aim of this three years monitoring project is to identify improvements in the entire heating system of all three buildings and investigate the potential of various solar systems regarding the regeneration of ground sources.

Oberfeld – Large PVT plants for ground source regeneration

In this P&D project the potential of large PVT plants used for ground source regeneration is studied.The complex Oberfeld consists of three buildings. Each of the three buildings has its separate heating system containing heat pumps, earth probes and a PVT solar plant. The PVT plant is one of the largest of its kind in Switzerland. The entire PVT plant consists of a total of 799 PVT collectors and has an overall area of more than 1300 m², distributed over the roofs of the three buildings. The heat from the PVT plant is primarily used for ground source regeneration, but it can also be used to provide heat directly for the evaporator of the heat pump.

Within this 5 years P&D project the interaction of the entire heating system will be optimized and the long term temperature development and behavior of the ground source with solar regeneration will by observed.

This project focuses on the use of a thermal driven adsorption heat pump using waste heat stemming from industrial processes.This project is supported by the Swiss National Science Foundation (SNSF). IBM research is leading the umbrella project; in addition to the SPF (adsorption heat pump development), the EMPA (Building Energy Materials and Components), the ETH Zürich (Complex Materials), the HEIG-VD (Solar Energetics and Building Physics) as well as the PSI (Technology Assessment Group) are implied in subparts of this project.

COMTES main purpose is the development and demonstration of various techniques enabling to store heat over a long period (seasonal storage) with a high energy density and with less losses than conventional water storage. This should enable to increase the building heat solar fraction coverage.At SPF, investigation are lead on an absorption/desorption concept using sodium hydroxide (NaOH) and water as thermochemical heat storage mediums. EMPA and Kingspan Renewables are SPF main project partner in this subproject line. The project is supported European Union's in the frame of the FP7 Research and Innovation funding programme (FP7, Project no. 295568).